The present invention relates to a device for reading out information stored in a storage layer. The device includes a radiation source for emitting a stimulation radiation, and a receiving device for receiving emission radiation emitted by the storage layer.
Especially for medical purposes, x-radiation is used to generate an image of an object, for example a patient, where said image is stored as a latent image in a storage layer. Most often, a phosphor carrier is used as the storage layer. The storage layer is stimulated using a radiation source to read out the x-radiation image stored in the storage layer. According to the stimulation, it will emit light with an intensity in proportion to the stored x-radiation image. The light emitted by the storage layer is received by a detection device and then converted into electrical signals such that the x-radiation image stored in the storage layer can then be made visible. For example, the x-radiation image may be presented directly on a monitor or it can be written onto a photographic x-ray film that is specifically applicable to x-ray images. Such an apparatus for reading out information stored in a storage layer is known, for example, from the published German Patent Application No. DE 197 52 925 A1. In this device, the light emitted by the storage layer is to be reproduced very precisely on the receiving device. The distance between the storage layer and the receiving device is kept to a minimum to increase the degree of compactness.
It is the principal objective of the present invention to enable a good quality reproduction of the information stored in a storage layer, such as a phosphor layer in an x-ray device.
This objective, as well as other objectives which will become apparent from the discussion that follows, are achieved by providing (a) a xe2x80x9cdistance devicexe2x80x9d, located between the receiving device and the storage layer, for setting a pre-specified distance between the receiving device and the storage layer, and (b) a xe2x80x9cdrive devicexe2x80x9d for imparting relative movement between the radiation source and the receiving device, on one hand, and the storage layer on the other.
According to the present invention, it is ensured that a pre-specified distance can be maintained between the receiving device and the storage layer. Preferably this distance is maintained as constant as possible and, furthermore, allows for very small settings by using the distance device such that a large amount of the radiation emitted by the stimulated storage layer can be detected by the receiving device. The distance device permits undesirable fluctuations of the distance that may occur to be quickly compensated. Such changes in distance may occur, for example, when the surface of the storage layer exhibits inaccuracies caused by the manufacturing process, or when external vibrations or impacts affect the device, which in turn affects the distance between the receiving device and the storage layer. Due to the distance device, contact between the storage layer and the receiving device, and thus a potential scratching, can be avoided. Furthermore, when presenting the x-ray image that was read out from the storage layer, artifact generation, a deviation of the local resolution and/or a bad image focus can be largely avoided.
According to the present invention, the reading device further incorporates a mechanism for imparting relative movement between the radiation source and the receiving device, on one hand, and the storage layer on the other. In this manner, the storage layer can be read out line by line such that the stored information is detected and converted into electrical signals.
Preferably, the distance device contains an air layer. With such an air layer, very small distances between the storage layer and the receiving device can be set. Air nozzles that are contained in the distance device can generate the air layer easily and precisely. These air nozzles are connected to an air supply.
In one advantageous embodiment of the invention, the device exhibits a transparent carrier material with the storage layer applied to this carrier. Thus, the receiving device is located on one side of the storage layer and the radiation source on the other. Another distance device can then be provided between the radiation source and the storage layer. This is particularly advantageous when a relative movement for exciting the storage layer is carried out between the storage layer and the radiation source, because contact between the radiation source and the storage layer can be avoided in this manner.
In another advantageous embodiment of the invention, the device exhibits a force mechanism, in particular a spring that can apply a force from the receiving device in the direction of the storage layer. This allows the reading device according to the invention to be used regardless of its position. The force mechanism provides a force for suitable setting of the distance, regardless of the direction of the forces of gravity affecting the receiving device.
For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention as illustrated in the accompanying drawings.